This invention relates, in general, to the patterning of metal on a semiconductor structure, and more particularly, to a method for providing a residue free plasma etch of a high temperature aluminum copper layer.
As integrated circuits become smaller and smaller in size in order to achieve a higher density semiconductor device, it becomes more important for the metal lines to become narrower and have better surface morphology. In order to achieve the better surface morphology and eliminate hillocks the metallization must be deposited at high temperatures. Typically speaking, high temperatures refer to those temperatures over 350.degree. C.
A typical metallization alloy is aluminum having approximately 1 to 4% copper. One of the disadvantages in using a high temperature deposited aluminum copper alloy is the etch residues left after patterning the metallization layer in a plasma process. This results, not only because of the non-volatility of the copper chlorides formed, but also due to the micro-masking caused by localized oxidation, primarily along the grain boundaries of the high temperature AlCu. Therefore, is would be desirable to provide a residue-free plasma etch process of high temperature aluminum copper.
Accordingly, it is an object of the present invention to provide a means to etch high temperature aluminum copper without leaving post-etch residues.
Another object of the present invention is to provide a method for residue-free etching of high temperature aluminum copper films.
Yet a further object of the present invention is to provide a procedure for etching a protective oxide coating and a high temperature aluminum copper layer in the same etcher.